As it is well known, on internal combustion engines at present available in commerce the fuel supply to the combustion chamber is increasingly more frequently achieved by means of one or several injectors housed inside suitable seats recessed into the engine head. Such injectors receive the fuel under high pressure from a fuel manifold which extends above the actual injectors.
The focal point of fuel supply groups described above is the connection between the injector and the fuel manifold which has to be achieved in such a manner as to exclude whatsoever fuel leakage. Such a connection nevertheless calls for design details which by frequently causing misalignment between the injector which projects from the recessed seating in the engine head and the fuel manifold located above the head, involves constraints by interposing between the injector and the fuel manifold a connection seal able to prevent any misalignment.
FIG. 1 illustrates a known coupling system between the engine head, the injector and the fuel manifold, in which the injector 100 is locked inside the seating 101 recessed in the head 102 by means of a securing strap 103 bolted into the head 102. The upper end of the injector 100 is connected to the fuel manifold 104 by means of a rigid bush 105 which has a first end placed on the injector 100 and a second end inserted into the inside of a corresponding seat 106 formed in the actual fuel manifold 104. The rigid bush 105 is coupled to the injector 100 and to the fuel manifold 104 with a certain clearance in such a manner as to make good the eventual unseating, and is held secured to the fuel manifold 104 by means of a flexible locking component 107 located on the outside of the rigid bush 105. The seal is ensured by means of two annular packings positioned to coincide with the two ends of the rigid bush 105.
It is manifest that a connection between injector and fuel manifold such as is shown in FIG. 1 is extremely costly, greatly complicates the assembly of the fuel supply group on the engine, and finally doubles the number of possible fuel leakage points.